It is known in the art that hydraulic and pneumatic filters may be used to remove particulates, oils and water vapor from fluid mixtures. These filters may also be used to remove odors from breathing air. It is known in the art that compressed air, which has several uses including in food packaging, pharmaceutical labs and integrated circuit manufacturing, may be treated to remove contaminants and water vapor. For instance, in circuit design, it is critical for the compressed air to be devoid of oils and water vapor which can cause a short circuit. Compressed air is treated before use in manufacturing systems to remove water vapor and contaminants from the air that may spoil the end product or at least increase the cost of production by robbing the system of power and efficiency.
Conventional filters, which are used in various applications such as in treating compressed air, may contain a two-piece housing including a filter head and an elongated tubular filter housing. An elongated tubular element is typically removably located within the housing, the tubular elements having annular end caps sealingly bonded at each end of a ring-shaped media. These filters also include a diverter or elbow structure which may direct flow into the filter and provide a means for separating the head casting into inlet and outlet streams, respectively connected to the inner and outer portions of the elongated tubular element.
More recently, filters have utilized a top cap that serves the function of a diverter. These top caps may have a truncated funnel-like configuration removably located within a cylindrical cavity of the head casting. The flow passes through the filter element, which may consist of a media or membrane designed to prevent undesired substances from flowing through the element into the filtrate product stream. Accordingly, filtrate that flows through the media then continues through the outlet port within the head casting. In coalescing filters, the media causes certain condensed liquid components to coalesce and combine the coalesced droplets out of the gaseous product stream while solid particles are trapped by sieving, impaction or Brownian motion.
The shape of the inlet-side surface of the top cap controls the flow geometry of the inlet flow into the element. Similarly, the outlet-side surface of the top cap controls the outlet flow. When the inlet stream directly impacts a wall portion of the top cap, the impact causes turbulence in the fluid flow. As a result, the kinetic energy of the fluid is decreased which increases the velocity of the fluid as it enters the filter element. These filters have included a top cap having a planar flange section which affects inlet flow from the head casting into the filter element. The flange may tend to reduce the effects of turbulence by decreasing the energy of the fluid and disturbing the velocity of the fluid as it enters the filter element. However, the planar flange may still result in turbulent flow in the inlet and outlet streams.
Accordingly, it is desirable to provide a fluid filter assembly having a flange which has inlet-side and outlet-side surfaces that enable more laminar flow of fluid directly into and out of the filter assembly. It is desirable to decrease turbulence because of the pressure drop and also because turbulence causes re-entrainment of condensed fluid in coalescing filters.